Examples of anti-noise measures applying adaptive signal processing have been reported and means for creating a noise cancellation field in an ambient environment of a sleeping person has been reported.
For example, noise cancellation pillows that creates a noise cancellation field while a person is sleeping have been proposed, in which an active noise control system, which creates a noise cancellation field around the person receiving noise while his/her sleep, is configured in the pillow (for example, refer to Patent Literature 1 and Patent Literature 2).